Yes, I already connected to Marvell sata 3 port with AHCI enable.

The best I got is 400mb read. Wondering is that possible my other setting or tweak that I can boost the reading speed back to 490~520mb as per advertise or average other ppl reading speed.

I just bought a new Plextor M5S 128GB SSD. I removed the old SATA hard drive from my laptop and plugged in the new SSD. I turned on my laptop with a Windows 7 installation disk inserted, booted from the Windows disk, and got the screen where it asks which drive to install Windows onto. It said there were no drives detected.

Then I restarted the computer and went into the BIOS and tried to do a "Hard drive diagnostic test" and it said "Hard drive not exist." The SSD also does not show up in the list of bootable devices.

Next, I put my old hard drive back into my laptop and put the SSD in a USB SATA hard drive enclosure. I plugged the enclosure into a USB port and loaded the BIOS again. I looked at the list of bootable devices and the SSD was listed. Then I loaded Windows. Windows did detect the SSD in the Disk Manager and from there I formatted the SSD. Now I am able to see the SSD listed in My Computer as drive "I".

I tried replacing the hard drive with the SSD again and the BIOS still will not detect it. It only detects it when it is plugged in through the USB enclosure. What do I need to do to get it to detect the SSD normally (plugged into the SATA cable inside the laptop)?

Bro, you are not alone.
I also encountered similar issue when i bought this to replace my old SSD.
Sometime can detect in BIOS, and sometime can't.
I check on Plextor forum, there is a few suggestions given :

1.Download and upgrade to latest firmware. (This have solved my problem!)
2.Change BIOS power saving mode into S3.
3.Replace Power Supply.

1. I already update the SSD to latest firmware (Problem NOT solve )
2. My BIOS do not have that power saving mode setting
3. Laptop can replace power supply?? 

1. I already update the SSD to latest firmware (Problem NOT solve )
2. My BIOS do not have that power saving mode setting
3. Laptop can replace power supply?? 

Maybe is compatibility issue of your laptop.
What is the brand / model and motherboard type?
Did you try to turn on ACHI in Bios?

I think I want to buy OCZ Vector 4 but not sure where to get it? Doesn't seem to be selling in lowyat shops and couldn't find lowyat topic selling it also..

Perhaps u mean vector or vertex 4  ?
Yea I didnt see either one of them in lowyat price list now. Instead, I saw a new line up of Vertex 450 from OCZ.
http://www.tomshardware.com/reviews/vertex...iew,3517-7.html

I think garage sellers may still have stock for vertex4  .

Guys, planning to get an SSD by month end, I'm looking to speed up my old AMD rig, an x3 710 on M4A785TD-V Evo. Read quite a few articles but still need to clear some Q's

1. Other than Plextor M5S 128GB, what else should l consider for a budget of RM300?
2. AHCI mode must be set before plugging in the SSD? looking to fresh install the OS
3. Same thing like HDD right? need to initialize & format before 1st use?
4. Anyone has the same mobo? any tips?

Any pointers will be of great help

For SSDs recomendation you should read this https://forum.lowyat.net/index.php?showtopi...post&p=61539477
But plextor SSD arent that bad, it was the a cheapest performance SSD i could buy when the price was still near 1GB = 1 dollar (in singapore lah)

2. yup, to avoid performance drop, switch to AHCI after installed OS is pain in the butt.
3. update the firmware before doing anything, but if install new OS you dont have to do anything, just like HDD.

the one i bolded is need to switch @ BIOS for all SSD?

Yup, some SandForce based SSD require AHCI mode to update its firmware, and it is necessary as it will improve performance compare to IDE mode, because you will get newer native AHCI driver from INTEL/AMD instead of default driver from Microsoft which may only treat your SSD like a HDD.
Newer mobo is default to AHCI, older one are mostly IDE if i recall correctly,

sorry intel520 120gb is sandforce? cause not reallly expert in SSD...

Yup

Source http://www.anandtech.com/show/5508/intel-s...ty-to-sandforce

Ya I got it wrong, heard vertex 4 has good reviews is vector newer and faster than vertex 4?

I decided to get Samsung 840 Pro. It is fastest compare to rest and only OCZ Vector beats it.

However reading the reviews, Samsung seems to be all positive while OCZ Vector has quite a number of negative reviews that says that the harddisk is blazingly fast while it works... which is just 2-3 months before it fails and need to send for warranty.

Yup, some SandForce based SSD require AHCI mode to update its firmware, and it is necessary as it will improve performance compare to IDE mode, because you will get newer native AHCI driver from INTEL/AMD instead of default driver from Microsoft which may only treat your SSD like a HDD.
Newer mobo is default to AHCI, older one are mostly IDE if i recall correctly,

In terms of release date from latest to oldest:
Vertex 450 > Vector > Vertex 4.
Hmm previously ocz is having lot of bad feedback at the production of older models. New models seem ok imo, but the easier way to check might just head to newegg website  .
Samsung 840 pro is expensive at higher capacity ones.
Yup, indeed  .
AHCI vs IDE is obvious at the "Welcome" screen loading time, AHCI just skipped it and IDE mode will load like HDD.
From boot screen to the Window Logo screen just almost the same speed imo.
Tested Intel 520 at old mobo sata2 [no AHCI]
while corsair force 3 in z68 mobo with AHCI enabled.